% Listing 7-7 - Support functions
 function res = ison( nm, cl )
% is this beam on the connection list, 
%        a cell array of beam names
% usage: res = ison( beam, cl )
 res = false;
 for in = 1:length(cl)
     item = cl{in};
     if strcmp(item, nm)
         res = true; break;
     end
 end
